Plasma processing system and pressure control method

Abstract

A plasma processing system comprising: a plasma processing chamber; an exhaust section for exhausting the plasma processing chamber, the exhaust valve provided in a path for exhausting gas inside the plasma processing chamber and for controlling the exhaust flow rate; and a control unit for controlling the pressure regulating valve to control the pressure in the plasma processing chamber, wherein the control unit controls the pressure regulating valve so that the pressure follows the set value when changing the pressure from a first pressure to a second pressure, by changing the set value from a first pressure value which becomes the first pressure to a second pressure value which becomes the second pressure, based on a first function, thereby causing the pressure to follow the set value.

Description

Technical Field

[0001] The present disclosure relates to a plasma processing system and a pressure control method.

Background Art

[0002] Patent Document 1 discloses a vacuum device including a pressure detection device that detects the pressure inside a processing chamber, a first exhaust passage connected to the processing chamber and provided with a first valve, and a second exhaust passage connected to the processing chamber and provided with a second valve. Further, Patent Document 1 discloses that the vacuum device further includes an exhaust device connected to the first exhaust passage and the second exhaust passage. Furthermore, Patent Document 1 discloses that the vacuum device further includes a control unit that controls the first valve and the second valve based on a detected pressure value detected by the pressure detection device and a set pressure value so that the pressure inside the processing chamber becomes a predetermined value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique for reducing variations in pressure fluctuations during exhaust in a plasma processing system.

Means for Solving the Problems

[0005] According to one aspect of the present disclosure, a plasma processing system is provided comprising: a plasma processing chamber; an exhaust section for exhausting the plasma processing chamber, the exhaust valve provided in a path for exhausting gas inside the plasma processing chamber and for controlling the exhaust flow rate; and a control unit for controlling the pressure regulating valve to control the pressure in the plasma processing chamber, wherein the control unit controls the pressure regulating valve so that the pressure follows the set value when changing the pressure from a first pressure to a second pressure, by changing the set value from a first pressure value which becomes the first pressure to a second pressure value which becomes the second pressure, based on a first function. [Effects of the Invention]

[0006] This disclosure provides a technology for reducing variations in pressure fluctuations in the exhaust gas in a plasma processing system. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a diagram illustrating the overview of the plasma processing system according to this embodiment. [Figure 2] Figure 2 illustrates the pressure changes in the plasma processing system according to this embodiment. [Figure 3] Figure 3 illustrates an example of a set value output by the control unit in the plasma processing system according to this embodiment. [Figure 4] Figure 4 illustrates an example of calculating the time constant in the set value output by the control unit in the plasma processing system according to this embodiment. [Figure 5] Figure 5 illustrates an example of calculating the time constant in the set value output by the control unit in the plasma processing system according to this embodiment. [Figure 6] Figure 6 illustrates an example of a set value output by the control unit in the plasma processing system according to this embodiment. [Figure 7]Figure 7 illustrates an example of calculating the time constant in the set value output by the control unit in the plasma processing system according to this embodiment. [Figure 8] Figure 8 illustrates an example of calculating the time constant in the set value output by the control unit in the plasma processing system according to this embodiment. [Figure 9] Figure 9 illustrates an example of a set value output by the control unit in the plasma processing system according to this embodiment. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments for carrying out this disclosure will be described with reference to the drawings. In this specification and the drawings, substantially identical components are denoted by the same reference numerals to avoid redundant explanations. For ease of understanding, the scale of the parts in the drawings may differ from that of the actual parts. In directions such as parallel, right angles, orthogonal, horizontal, vertical, up and down, and left and right, deviations are permitted to the extent that they do not impair the effect of the embodiment. The shape of the corners is not limited to right angles and may be rounded. Parallel, right angles, orthogonal, horizontal, and vertical may include substantially parallel, substantially right angles, substantially orthogonal, substantially horizontal, and substantially vertical.

[0009] The following describes an example of the configuration of a plasma processing system. By describing the plasma processing system, we will explain the pressure control method using the plasma processing system. Figure 1 is a diagram illustrating the overview of a plasma processing system 100, which is an example of a plasma processing system according to this embodiment. Figure 1 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus 1 included in the plasma processing system 100.

[0010] The plasma processing system 100 includes a capacitively coupled plasma processing apparatus 1 and a control unit 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply system 30, and an exhaust unit 40. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support unit 11 is located inside the plasma processing chamber 10. The shower head 13 is located above the substrate support unit 11. In one embodiment, the shower head 13 constitutes at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, the side walls 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s, and at least one gas outlet for discharging gas from the plasma processing space. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0011] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of the substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 in a plan view. The substrate W is placed on the central region 111a of the main body portion 111, and the ring assembly 112 is placed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also called the substrate support surface for supporting the substrate W, and the annular region 111b is also called the ring support surface for supporting the ring assembly 112.

[0012] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic chuck electrode 1111b placed within the ceramic member 1111a. The electrostatic chuck electrode 1111b is also called a clamping electrode. In one embodiment, the electrostatic chuck electrode 1111b is electrically connected or coupled to a chuck power supply. The chuck power supply may be a DC power supply or an AC power supply. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Furthermore, other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have an annular region 111b. In this case, the ring assembly 112 may be placed on the annular electrostatic chuck or the annular insulating member, or on both the electrostatic chuck 1111 and the annular insulating member. In addition, at least one bias electrode, electrically connected or coupled to the power supply 31 and / or power supply 32 described later, may be placed within the ceramic member 1111a. In this case, at least one bias electrode functions as a lower electrode. Also, the conductive member of the base 1110 and the bias electrode in the ceramic member 1111a may function as multiple lower electrodes. In one embodiment, the first voltage generation unit 32a, which functions as a voltage pulse generation unit described later, is electrically connected or coupled to the bias electrode in the ceramic member 1111a, and the first RF generation unit 31a, described later, is electrically connected or coupled to the conductive member of the base 1110. Furthermore, the electrostatic chuck electrode 1111b may function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0013] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one covering ring. The edge rings are formed of a conductive or insulating material, and the covering rings are formed of an insulating material.

[0014] The substrate support section 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid, such as brine or gas, flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are arranged within the ceramic member 1111a of the electrostatic chuck 1111. The substrate support section 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0015] The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlet ports 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s through the plurality of gas inlet ports 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0016] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one processing gas from a corresponding gas source 21 to the shower head 13 through a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Further, the gas supply unit 20 may include one or more flow modulation devices that modulate or pulse the flow rate of at least one processing gas.

[0017] The power supply system 30 includes a power supply 31 that is electrically connected or coupled to the plasma processing chamber 10. In one embodiment, the power supply 31 is electrically connected or coupled to the plasma processing chamber 10 through at least one impedance matcher. The impedance matcher may be a mechanically controlled matcher or an electronically controlled matcher. The power supply 31 is configured to supply at least one RF (Radio Frequency) signal (RF power) to at least one lower electrode and / or at least one upper electrode. Thereby, plasma is generated from at least one processing gas supplied to the plasma processing space 10s. Therefore, the power supply 31 can function as at least a part of a plasma generation unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. Also, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and the ion component in the formed plasma can be drawn into the substrate W.

[0018] The power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode, and is configured to generate a source RF signal (source RF power) to generate plasma in the plasma processing space 10s. In one embodiment, the first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matcher. In one embodiment, the source RF signal has a frequency within the range of 10 MHz to 150 MHz. In one embodiment, the first RF generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0019] The second RF generation unit 31b is electrically connected or coupled to at least one lower electrode and is configured to generate a bias RF signal (bias RF power). In one embodiment, the second RF generation unit 31b is electrically connected or coupled to at least one lower electrode via at least one impedance matcher. When the first RF generation unit 31a is electrically connected or coupled to the lower electrode, the second RF generation unit 31b may be electrically connected or coupled to the same lower electrode or to another lower electrode. The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency within the range of 100 kHz to 60 MHz. In one embodiment, the second RF generation unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0020] The power supply system 30 may also include a power supply 32 that is electrically connected to or coupled to the plasma processing chamber 10. The power supply 32 includes a first voltage generation unit 32a and a second voltage generation unit 32b. In one embodiment, the first voltage generation unit 32a is electrically connected to or coupled to at least one lower electrode and configured to generate a first voltage signal. The generated first voltage signal is applied to at least one lower electrode. In one embodiment, the second voltage generation unit 32b is electrically connected to or coupled to at least one upper electrode and configured to generate a second voltage signal. The generated second voltage signal is applied to at least one upper electrode.

[0021] In various embodiments, the first and / or second voltage signals may be pulsed. In this case, the first voltage generation unit 32a and / or the second voltage generation unit 32b function as voltage pulse generation units configured to generate a sequence of voltage pulses. Thus, the sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. In one embodiment, the sequence of voltage pulses has multiple cycles, each cycle including a burst of voltage pulses in a first period and a constant reference voltage in a second period. That is, the burst of voltage pulses is repeated in the sequence of voltage pulses. The absolute value of the voltage level of the voltage pulse is greater than the absolute value of the voltage level of the reference voltage. The voltage pulse may have an arbitrary waveform having a rectangle, trapezoid, triangle, or a combination thereof, and the arbitrary waveform may change over time. The voltage pulse may have positive polarity or negative polarity. The sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. The first and second voltage generation units 32a and 32b may be provided in addition to the power supply 31, and the first voltage generation unit 32a may be provided in place of the second RF generation unit 31b.

[0022] The exhaust section 40 may be connected to, for example, a gas outlet 10e located at the bottom of the plasma processing chamber 10. The exhaust section 40 includes a pressure regulating valve 41 and a vacuum pump 42. The pressure regulating valve 41 regulates the pressure within the plasma processing space 10s. The pressure regulating valve 41 is located in the path for exhausting gas from inside the plasma processing chamber 10. The pressure regulating valve 41 controls the flow rate of the exhaust gas. The vacuum pump 42 may include a turbomolecular pump, a dry pump, or a combination thereof.

[0023] To measure the pressure in the plasma processing space 10s, the plasma processing apparatus 1 is equipped with a pressure gauge 43 in the plasma processing chamber 10. The pressure regulating valve 41 is controlled by the control unit 2 so that the pressure in the plasma processing space 10s, as measured by the pressure gauge 43, becomes a desired pressure. For example, the control unit 2 controls the opening degree of the pressure regulating valve 41. The pressure regulating valve 41 is, for example, a pendulum valve or a vent valve. Alternatively, for example, the output of the vacuum pump 42 may be controlled to be constant.

[0024] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various processes described herein. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, some or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 is implemented, for example, by a computer 2a. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The functions implemented by the processing unit 2a1 described herein may be implemented in a circuit or processing circuitry, including a general-purpose processor, an application-specific processor, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (Central Processing Unit), conventional circuitry, and / or a combination thereof, programmed to implement the functions described herein. A processor is considered a circuit or processing circuit, including transistors and other circuitry. A processor may be a programmed processor that executes a program stored in the storage unit 2a2. This program may be stored in the memory unit 2a2 in advance, or it may be retrieved via a medium when needed. The retrieved program is stored in the memory unit 2a2 and read from the memory unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The memory unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).In this disclosure, circuits, units, and means are hardware programmed to perform or configured to perform the functions described. Such hardware may be any hardware described in this disclosure, or any hardware known to be programmed to perform or execute the functions described. If such hardware is a processor that is considered to be a type of circuit, such circuit, means, or unit is a combination of hardware and software used to constitute such hardware and / or processor.

[0025] In semiconductor manufacturing equipment, the necessary gases for process processing are supplied to the plasma processing chamber. Furthermore, in semiconductor manufacturing equipment, the gas exhaust volume of turbomolecular pumps or dry pumps connected to the plasma processing chamber is controlled to adjust the pressure inside the plasma processing chamber to a desired value.

[0026] In semiconductor manufacturing equipment, the exhaust volume is adjusted using an exhaust control valve that can change the conductance of the exhaust flow path.

[0027] To adjust the pressure within the plasma processing chamber, a pressure gauge connected to the chamber measures the pressure inside the chamber. The opening of the exhaust control valve is then manipulated so that the measured pressure inside the plasma processing chamber becomes the desired pressure. The valve opening of the exhaust control valve is determined by the control unit using control technology such as PID (Proportional-Integral-Differential) control. The control unit uses the pressure value to be stabilized as the set value, the result measured by the pressure gauge as the state value, and the position of the exhaust control valve as the control value, and manipulates the opening of the exhaust control valve so that the state value matches the set value.

[0028] In conventional technology, the set value given to the control unit during pressure adjustment is the pressure value to be stabilized. Conventional technology does not impose any constraints on the trajectory to reach the set pressure.

[0029] In conventional technology, the trajectory to reach the set pressure is not constrained and is therefore affected by the volume of the gas flow path and the conductance in the gas flow path. Because it is affected by the volume of the gas flow path or the conductance in the gas flow path, if there is a difference in the volume of the gas flow path or the conductance in the gas flow path, the pressure trajectory showing the pressure change will also change.

[0030] Let's explain using a specific example. Figure 2 is a diagram illustrating the change in pressure in a plasma processing system 100, which is an example of a plasma processing system according to this embodiment.

[0031] In Figure 2, the horizontal axis represents time, and the vertical axis represents pressure. Line SV represents the set value, while lines PV1, PV2, and PV3 represent state values. Lines PV1, PV2, and PV3 have different conditions, such as the volume of the gas flow path or the conductance in the gas flow path. At time t1, as shown by line SV, control unit 2 increases the set value in a stepwise manner from pressure P1 to pressure P2. At time t2, as shown by line SV, control unit 2 decreases the set value in a stepwise manner from pressure P2 to pressure P3.

[0032] As shown by line SV in Figure 2, even when controlled based on the same setpoint, the pressure changes vary due to the state of the plasma processing chamber, as indicated by lines PV1, PV2, and PV3 in Figure 2.

[0033] Plasma processes such as etching involve multiple steps with different process conditions, during which the type and flow rate of supplied gas and the pressure of the plasma processing chamber are changed. Conventionally, when changing conditions between steps, plasma generation was stopped before the change, and plasma generation was restarted only after the state values ​​had stabilized from the conditions of the previous step to the conditions of the subsequent step.

[0034] However, to avoid particle generation due to plasma shutdown and throughput reduction due to the time required for state stabilization between steps, processing methods are now shifting to those that continue plasma generation even when conditions are changed between steps. When plasma generation is continued even when conditions are changed, the process is maintained even when conditions are changed, so the process results may differ depending on the degree of condition change.

[0035] The volume and conductance of the gas flow path in a plasma processing apparatus can vary depending on the assembly of the components. Furthermore, these variations can occur due to changes in gas flow over time as the apparatus is used. As mentioned earlier, the pressure adjustment of the plasma processing chamber will differ between steps due to these variations. Moreover, even when performing process processing under the same conditions using identical components in similar apparatuses, inconsistencies in processing results can occur. Such inconsistencies in processing results can lead to a decrease in process yield.

[0036] The differences in the degree of condition changes that lead to the aforementioned yield reduction arise because, in conventional pressure adjustment, only the stable pressure is constrained, and the trajectory leading up to that pressure is not constrained. Therefore, the plasma processing system in this disclosure changes the pressure gradually along a desired trajectory from the start of the pressure change until the stable pressure. By changing the pressure gradually along a desired trajectory, the pressure can be changed while following a set value that defines the trajectory. Specifically, the plasma processing system in this disclosure changes the set value in pressure control based on a function of the set value of pressure with respect to time. By changing the set value in pressure control based on a function of the set value of pressure with respect to time, it is possible to prevent different trajectories from occurring between devices even if there are differences in the devices that cause changes in the trajectory of the pressure change.

[0037] The specific change from the conventional technology is that, in addition to the pressure to be stabilized, the control unit is also given a set value for the trajectory leading up to that pressure (hereinafter referred to as the reference trajectory). The reference trajectory can be any trajectory, including, for example, a linear shape or a saturation curve shape.

[0038] The control unit 2 gradually changes the trajectory of the pressure set value along the reference trajectory until a stable pressure is reached. Figure 3 is a diagram illustrating an example of a set value SV1 output by the control unit 2 in a plasma processing system 100, which is an example of a plasma processing system according to this embodiment. Figure 3 shows an example in which the control unit 2 changes the set value along the saturation curve.

[0039] From time t1, as shown by line SV1, the control unit 2 increases the set value so that it changes along the saturation curve from pressure P1 (an example of the first pressure) to pressure P2 (an example of the second pressure). In other words, the control unit 2 changes the set value SV1 based on a function (an example of the first function) in which the set value SV1 changes along the saturation curve from pressure P1 (an example of the first pressure) to pressure P2 (an example of the second pressure) with respect to time. Also, from time t2, as shown by line SV1, the control unit 2 decreases the set value so that it changes along the saturation curve from pressure P2 (an example of the first pressure) to pressure P3 (an example of the second pressure). In other words, the control unit 2 changes the set value SV1 based on a function (an example of the first function) in which the set value SV1 changes along the saturation curve from pressure P2 (an example of the first pressure) to pressure P3 (an example of the second pressure) with respect to time.

[0040] The setting value SV1 is calculated, for example, based on Equation 1.

[0041]

number

[0042] Note that Pe represents the final pressure value to be set (an example of a second pressure value), Ps represents the current (initial) pressure value (an example of a first pressure value), t represents time, and τ represents the time constant. The right-hand side of Equation 1 is an example of the first function.

[0043] The calculation of the time constant τ will now be explained. The time constant τ is determined based on the pressure response when the pressure regulating valve 41 is operated. Figures 4 and 5 illustrate examples of calculating the time constant τ at a set value output by the control unit 2 in a plasma processing system 100, which is an example of a plasma processing system according to this embodiment. Figure 4 is an example of calculating the time constant τ when the pressure is increased. Figure 5 is an example of calculating the time constant τ when the pressure is decreased.

[0044] The reference trajectory, which is the trajectory until the pressure stabilizes at the set pressure, can be arbitrarily determined. On the other hand, the shortest trajectory, which takes the shortest time, can be determined from the pressure measurement values. The shortest trajectory can be estimated from the trajectory when opening the pressure regulating valve 41 from fully open (maximum opening) to fully closed (minimum opening) or when opening the pressure regulating valve 41 from fully closed (minimum opening) to fully open (maximum opening).

[0045] In Figures 4 and 5, pressure Pmax represents the pressure when the pressure regulating valve 41 is fully closed. In Figures 4 and 5, pressure Pmin represents the pressure when the pressure regulating valve 41 is fully open.

[0046] As an example, let's consider the case of increasing the pressure. In Figure 4, the pressure regulating valve 41 is fully open up to time t11. Therefore, up to time t11, the pressure is at its lowest point, Pmin.

[0047] At time t11, the control unit 2 instructs the pressure regulating valve 41 to be fully closed. When the pressure regulating valve 41 is fully closed, the pressure gradually increases and finally converges to the highest pressure Pmax at time t12. Here, if pressure Pmin is set to 0% and pressure Pmax is set to 100%, then pressure Pm is set to 63% of that pressure.

[0048] The control unit 2 calculates the time Δt1 from the start of the pressure increase at time t11 until the pressure rises from pressure Pmin to pressure Pm. Then, the control unit 2 sets time Δt1 as the time constant τ.

[0049] Furthermore, let's explain the case of decreasing the pressure as an example. In Figure 5, at time t21, the pressure regulating valve 41 is fully closed. Therefore, up to time t21, the pressure is at its highest pressure Pmax.

[0050] At time t21, the control unit 2 instructs the pressure regulating valve 41 to be fully opened. When the pressure regulating valve 41 is fully opened, the pressure gradually decreases, and finally, at time t22, the pressure converges to the lowest pressure Pmin. Here, if pressure Pmax is set to 0% and pressure Pmin to 100%, then pressure Pn is set to 63%.

[0051] The control unit 2 calculates the time Δt2 from the start of the pressure decrease at time t21 until the pressure decreases from pressure Pmax to pressure Pn. Then, the control unit 2 sets the time Δt2 as the time constant τ.

[0052] Next, an example is shown in which the control unit 2 changes the set value along a straight line. Figure 6 is a diagram illustrating an example of a set value SV2 output by the control unit 2 in a plasma processing system 100, which is an example of a plasma processing system according to this embodiment. Figure 6 shows an example in which the control unit 2 changes the set value along a straight line.

[0053] From time t1, as shown by line SV2, the control unit 2 increases the set value so that it changes linearly from pressure P1 (an example of the first pressure) to pressure P2 (an example of the second pressure). In other words, the control unit 2 changes the set value SV2 based on a function (an example of the first function) in which the set value SV2 changes linearly with respect to time from pressure P1 (an example of the first pressure) to pressure P2 (an example of the second pressure). Then, from time t2, as shown by line SV2, the control unit 2 decreases the set value so that it changes linearly from pressure P2 (an example of the first pressure) to pressure P3 (an example of the second pressure). In other words, the control unit 2 changes the set value SV2 based on a function (an example of the first function) in which the set value SV2 changes linearly with respect to time from pressure P2 (an example of the first pressure) to pressure P3 (an example of the second pressure).

[0054] The set value SV2 is calculated, for example, based on Equation 2.

[0055]

number

[0056] Note that Pe represents the final pressure value to be set, Ps represents the current (initial) pressure value, t is time, and a is the proportionality constant indicating the slope of the line. The right-hand side of Equation 2 is an example of the first function.

[0057] The calculation of the proportionality constant a will now be explained. The proportionality constant a is determined based on the pressure response when the pressure regulating valve 41 is operated. Figures 7 and 8 illustrate examples of calculating the proportionality constant a at a set value output by the control unit 2 in a plasma processing system 100, which is an example of a plasma processing system according to this embodiment. Figure 7 is an example of calculating the proportionality constant a when the pressure is increased. Figure 8 is an example of calculating the proportionality constant a when the pressure is decreased.

[0058] In Figures 7 and 8, pressure Pmax represents the pressure when the pressure regulating valve 41 is fully closed. Also, in Figures 7 and 8, pressure Pmin represents the pressure when the pressure regulating valve 41 is fully open.

[0059] As an example, let's consider the case of increasing the pressure. In Figure 7, the pressure regulating valve 41 is fully open up to time t13. Therefore, up to time t13, the pressure is at its lowest point, Pmin.

[0060] At time t13, the control unit 2 instructs the pressure regulating valve 41 to be completely closed. When the pressure regulating valve 41 is completely closed, the pressure gradually increases and finally converges to the highest pressure Pmax at time t14. The pressure difference (pressure fluctuation) between pressure Pmin and pressure Pmax is the differential pressure ΔP, and the time from time t13 to time t14 is time Δt3.

[0061] Then, the control unit 2 calculates the proportionality constant a by dividing the differential pressure ΔP by the time Δt3.

[0062] Furthermore, let's consider the case of decreasing the pressure as an example. In Figure 8, the pressure regulating valve 41 is fully closed up to time t23. Therefore, up to time t23, the pressure is at its highest pressure, Pmax.

[0063] At time t23, control unit 2 instructs to fully open the pressure regulating valve 41. When the pressure regulating valve 41 is fully opened, the pressure gradually decreases, and finally, at time t24, the pressure converges to the lowest pressure Pmin. The pressure difference (pressure fluctuation) between pressure Pmin and pressure Pmax is the differential pressure ΔP, and the time from time t23 to time t24 is time Δt4.

[0064] Then, the control unit 2 calculates the proportionality constant a by dividing the differential pressure ΔP by the time Δt4.

[0065] Alternatively, the shortest reference orbit obtained from the mathematical model may be used as is. For example, when using the shortest reference orbit obtained from the mathematical model, the time to reach stability may be changed to a time greater than 1x the shortest orbit, for example, 1.2x, in order to ensure a control margin.

[0066] Note that the first function is not limited to the examples in Equation 1 and Equation 2; any function that can change while tracking the set value may be used. Changing while tracking the set value means, for example, that the difference between the pressure value and the set value remains within a predetermined range, for example, within a range where the difference is zero or can be considered as having no difference. However, in the case of a step function, as illustrated in Figure 2, the pressure cannot change while tracking the set value, so the first function is a function other than a step function that changes directly from the first pressure to the second pressure. However, if time can be divided into small time intervals from the first pressure to the second pressure, and the pressure can change while tracking the set value in each divided time interval, then a step function may be used in each time interval.

[0067] Another example of the control unit 2 changing the set value along a straight line is shown. Figure 9 is a diagram illustrating an example of a set value SV3, which is an example of a set value output by the control unit 2 in a plasma processing system 100, which is an example of a plasma processing system according to this embodiment. Figure 3 shows an example of the control unit 2 changing the set value along a broken line.

[0068] From time t31, as shown by line SV3, control unit 2 increases the set value so that it changes linearly from pressure P11 to pressure P12. In other words, control unit 2 changes the set value SV3 based on a function in which the set value SV3 is a linear function with respect to time from pressure P11 to pressure P12. Also, from time t32, as shown by line SV3, control unit 2 increases the set value so that it changes linearly from pressure P12 to pressure P13. In other words, control unit 2 changes the set value SV3 based on a function in which the set value SV3 is a linear function with respect to time from pressure P12 to pressure P13.

[0069] The setting value SV3 is calculated, for example, based on Equation 2, similar to the setting value SV2.

[0070] When the control unit 2 changes the pressure from pressure P11 to pressure P13 between time t11 and time t13, it changes the set value SV3 at time t12 between time t11 and time t13 so that the pressure P12 is between pressure P11 and pressure P13. In other words, when the control unit 2 changes the pressure from the first pressure to the second pressure from the first time to the second time, it may control the pressure to be an intermediate pressure between the first pressure and the second pressure at a predetermined time between the first time and the second time.

[0071] In the example with setting value SV3, the setting value SV3 changes along a straight line, but it may also be made to change along a saturation curve.

[0072] According to the plasma processing system of this embodiment, since the trajectory is the same when process conditions change between devices, it is possible to avoid a decrease in yield due to inconsistencies in process processing.

[0073] The substrate processing system according to the present embodiment disclosed herein should be considered in all respects as illustrative and not restrictive. The above embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be otherwise configured and combined in a non-consistent manner.

[0074] This application claims priority to Basic Patent Application No. 2025-013235, filed with the Japan Patent Office on January 29, 2025, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0075] 1. Plasma processing equipment 2 Control Unit 10 Plasma processing chamber 20 Gas Supply Department 30 Power Systems 40 Exhaust section 100 Plasma Processing Systems PV1, PV2, PV3, SV wire SV1, SV2, SV3 settings W board

Claims

1. Plasma processing chamber and An exhaust section is provided in the path for exhausting the gas inside the plasma processing chamber, and includes a pressure regulating valve for controlling the exhaust flow rate, and exhausts the plasma processing chamber. A control unit controls the pressure regulating valve to control the pressure in the plasma processing chamber, Equipped with, When the control unit changes the pressure from the first pressure to the second pressure, it changes the set value from the first pressure value which becomes the first pressure to the second pressure value which becomes the second pressure based on the first function, thereby controlling the pressure adjustment valve so that the pressure follows the set value and the pressure becomes the set value. The first function is a function in which the set value changes with respect to time from a first pressure value to a second pressure value along a saturation curve. Plasma processing system.

2. The time constant showing the saturation curve is determined based on the pressure response when the pressure regulating valve is operated. The plasma processing system according to claim 1.

3. A plasma processing chamber, An exhaust section is provided in the path for exhausting the gas inside the plasma processing chamber, and includes a pressure regulating valve for controlling the exhaust flow rate, and exhausts the plasma processing chamber. A control unit controls the pressure regulating valve to control the pressure in the plasma processing chamber, Equipped with, When the control unit changes the pressure from the first pressure to the second pressure, it changes the set value from the first pressure value which becomes the first pressure to the second pressure value which becomes the second pressure based on the first function, thereby controlling the pressure adjustment valve so that the pressure follows the set value and the pressure becomes the set value. The first function is a function in which the set value is a linear function with respect to time from the first pressure value to the second pressure value, The constant representing the slope of the aforementioned linear function is determined based on the pressure response when the pressure regulating valve is operated. Plasma processing system.

4. When the control unit changes the pressure from the first pressure to the second pressure from the first time to the second time, it controls the pressure to become an intermediate pressure between the first pressure and the second pressure at a predetermined time between the first time and the second time. A plasma processing system according to any one of claims 1 to 3.

5. A pressure control method for a plasma processing system comprising a plasma processing chamber and an exhaust section for exhausting gas from inside the plasma processing chamber, the exhaust section being provided in a path for exhausting gas from inside the plasma processing chamber and equipped with a pressure regulating valve for controlling the exhaust flow rate, the method being used to control pressure in a plasma processing system, When changing the pressure in the plasma processing chamber from a first pressure to a second pressure, the pressure regulating valve is controlled so that the pressure follows the set value by changing the set value from a first pressure value that becomes the first pressure to a second pressure value that becomes the second pressure, based on a first function, thereby making the pressure follow the set value. The first function is a function in which the set value changes with respect to time from a first pressure value to a second pressure value along a saturation curve. Pressure control method.

6. The time constant showing the saturation curve is determined based on the pressure response when the pressure regulating valve is operated. The pressure control method according to claim 5.

7. A pressure control method in a plasma processing system comprising a plasma processing chamber and an exhaust section for exhausting the plasma processing chamber, the exhaust section being provided in a path for exhausting gas inside the plasma processing chamber and equipped with a pressure regulating valve for controlling the exhaust flow rate, the method being used to exhaust the plasma processing chamber. When changing the pressure in the plasma processing chamber from a first pressure to a second pressure, the pressure regulating valve is controlled so that the pressure follows the set value by changing the set value from a first pressure value that becomes the first pressure to a second pressure value that becomes the second pressure, based on a first function, thereby making the pressure follow the set value. The first function is a function such that the pressure is a linear function with respect to time, The constant representing the slope of the aforementioned linear function is determined based on the pressure response when the pressure regulating valve is operated. Pressure control method.

8. When changing from the first pressure to the second pressure from the first time point to the second time point, the pressure is controlled to become an intermediate pressure between the first and second pressures at a predetermined time between the first and second time points. The pressure control method according to any one of claims 5 to 7.

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